Ventilator cowls



March 24,1959

Filed March 18, 1957 O. D. NIBLETT VENTILATOR COWLS 2 Sheets-Sheet 1 March 24, 1959 o. D. NIBLETT 2, 7 45 VENTILATOR COWLS Filed March 18, 1957 2 Sheetsl-Sheec 2 United States Patent VENTILATOR COWLS Oswald Dorrington Niblett, London, England Application March 18, 1957, Serial No. 646,781

Claims priority, application Great Britain May 15, 1956 1 Claim. (Cl. 98-82) This invention relates to ventilator cowls applicable to chimneys or Ventilation conduits and adapted, under the influence of external air currents, to exert an extractor or suction action on the chimney or ventilator conduit.

The present invention has for its object to provide an improved construction of ventilator cowl whereby a more effective extractor or suction action resulting from external air currents may be achieved.

The invention includes a ventilator cowl comprising an external structure including four symmetrically disposed sides in the form of rectangular plates curved to an arcuate formaiton in plan and disposed with the convex side inwards and with vertical edges of adjacent plates spaced apart to provide openings, an internal pipe coaxial with the external structure and having at least a portion of its length substantially co-extensive with the external structure and spaced from the convex inner faces of said sides, slots extending downwardly from the upper end of said internal pipe and located substantially opposite the middle of said sides, and a cap plate closing the upper end of said internal pipe.

The invention is hereinafter described, by way of example, with reference to the accompanying diagrammatic drawings, in which:

Fig. 1 is a perspective view illustrating one embodiment of ventilator cowl according to the invention;

Fig. 2 is a vertical section of the cowl;

Fig. 3 is a section on the line IIIIII, Fig. 2; and

Fig. 4 is a diagram illustrating the manner in which air currents exert an extractor action.

In carrying the invention into effect according to a particular embodiment, and with reference to the accompanying diagrammatic drawings, a ventilator cowl according to the invention comprises an internal pipe 1 which may have a part la projecting downwards from a swaged rim 1b for insertion into a chimney pot or the open end of a ventilator conduit so as to provide a stackpipe exten sion. Metal straps 2 or hooks for fixing purposes may be fitted around the lower part of the internal pipe 1. The external structure of the cowl comprises a number of sides 3, preferably three or four, each side being of partcylindrical formation disposed parallel to the axis of the internal pipe and with the convex side spaced from the wall of the pipe 1, i. e. tangentially to a circle of larger diameter than the internal pipe. The sides are connected in spaced-apart relation by brackets or cross-pieces 3a at top and bottom.

The internal pipe 1 is formed with symmetrically disposed axially extending slots 1c equal in number to the number of sides 3. The slots may extend downwardly from the upper end of the internal pipe 1 and at the bottom of each slot a bracket 1d may be formed by an outwardly bent portion of the Wall of the internal pipe 1.

The external structure comprising the sides 3 connected together in spaced relation is disposed coaxially around the slotted portion of the internal pipe 1 with the axial slots 10 of the internal pipe 1 substantially opposite the middle of the respective sides 3. The brackets 1d at the bottom of the slots 10 in the pipe 1 are connected to the respective convex sides 3 at or adjacent their lower end, and the upper end of the internal pipe 1 may be closed by means of a square cap plate 4 having the corners bent over for connection to the sides 3. Pins or the like projecting downwardly from the cap plate 4 may locate the upper end of the internal pipe 1 As shown in Fig. 4, it will be seen that external air currents, for example, in the direction of the arrow A, will flow into openings 3b between the sides 3 on the windward side of the cowl and will pass through the spaces between the side plates 3 and the internal pipe 1 and out through openings 3c at the leeward side. Air currents passing at increased velocity through the restricted parts of said spaces in the region of the slots 10 exert an extractor or suction action at the slots 10 as indicated by the arrows.

Where increased suction action is necessary, for instance, to counteract an unusually strong tendency to down-draught in a chimney, the area of the axially extending slots of the internal pipe may be substantially less than the area of the openings 3b, 3c between the adjacent sides of the external structure. Alternatively, or in addi tion, the spacing between the sides of the external structure and the base of the internal pipe where the axially extending vents or vented regions are provided, may be reduced so as to increase the velocity of the air currents flowing past said vents or vented regions.

I claim:

A sheet metal ventilator cowl comprising a vertical internal cylindrical pipe having a lower portion adapted for connection to a fluid conduit and an upper portion provided with four vertical slots symmetrically spaced circumferentially, an external metal structure surrounding the upper portion of said internal pipe comprising four spaced side plates circumferentially arranged about and spaced from said internal pipe, each of said side plates being substantially rectangular and centrally curved to arcuate formation about a vertical axis of curvature, said side plates being disposed with the convex sides thereof adjacent and spaced from said internal pipe opposite the vertical slots therein, the vertical edges of adjacent plates being spaced apart to provide lateral openings therebetween, the area of each of said lateral openings being less than half the area of each of said arcuate rectangular plates, a cap plate of substantially square configuration closing the upper end of said internal pipe and connected at its corners to the upper ends of said side plates at the middle portions thereof so that the vertical edges of said side plates project outwardly of said cap plate to provide apertures adjacent the top and bottom of each of the lateral openings between the side plates, and brackets connecting the lower part of the side plates in spaced relation to said internal pipe.

References Cited in the file of this patent UNITED STATES PATENTS 646,371 Pancoast Mar. 27, 1900 1,509,996 Elting Sept. 30, 1924 2,269,428 Breidert Jan. 13, 1942 2,340,410 Chancellor Feb. 1, 1944 FOREIGN PATENTS 948,146 France Ian. 24, 1949 804,449 Germany Apr. 23, 1951 487,161 Canada Oct. 14, 1952 

